Locking system for a motor vehicle

Abstract

Locking system for access and / or driving authorization in a motor vehicle (1) comprising a first device (4) having at least two states and designed as a control device, and a corresponding second device (5), wherein the two devices (4, 5) have transmitters and / or receivers (24, 17) for electromagnetic signals (7) for their intended operation, wherein the transmitter (17) is operated with a transmission channel (19) having a predetermined transmission frequency, and wherein at least one of the signals (7) transmitted between the second device (5) and the first device (4) is a coded operating signal (15) for authentication of the second device (5), such that, after positive evaluation of the transmitted operating signal (15) by the authorized second device (5), a change in the state of the first device (4) can be effected, characterized in that the transmission frequency can be adjusted by means of a PLL (Phase-locked Loop) synthesizer (21) having a quartz crystal (25), which is a Delta-Sigma Fractional N-PLL synthesizer.

Description

[0001] The invention relates to a locking system according to the preamble of claim 1.

[0002] For increased security requirements, electronic locking systems that operate using electromagnetic waves are employed. Particularly in motor vehicles, such locking systems are used as door locking systems for access authorization and / or as ignition lock systems, steering locks, immobilizers, engine control units, or similar components for driving authorization.

[0003] Such locking systems are known from DE 43 40 260 A1. The locking system consists of a first device, designed as a control unit for locking and / or unlocking car doors in the manner of a central locking system or ignition lock, and an associated second device designed in the manner of an electronic key. For their intended operation, both devices have transmitters and / or receivers for transmitting electromagnetic radio signals. In intended operation, at least one signal can be transmitted between the key and the control unit as a coded operating signal for authenticating the key, so that after a positive evaluation of the transmitted operating signal, and thus with an authorized key, a change in the state of the control unit can be effected.The transmitter is operated with a transmission channel that has a predetermined transmission frequency; therefore, in such radio locking systems, the data is transmitted on a radio channel.

[0004] Such locking systems have also been further developed with so-called "keyless" functionalities. With "Keyless Entry" or "Passive Entry" functionality, manual operation of the electronic key by the user is no longer necessary. It is sufficient for the user to carry the key. The operating signal for access authorization is then automatically transmitted between the two systems when the user is within range of the vehicle and, for example, operates the door handle. Similarly, these locking systems can feature "Keyless Go" or "Passive Go" functionality, whereby the operating signal for driving authorization is automatically transmitted between the two systems when the user is inside the vehicle and, for example, presses a start / stop button on the dashboard.

[0005] In the case of remote locking systems for motor vehicles, a narrow frequency band of 433.92 MHz ± 900 kHz is used in Europe. Narrowband radio systems require crystals with very low tolerance to meet various requirements, such as legal regulations. However, these crystals are very expensive.

[0006] Further state of the art is given by documents DE 196 45 808 A1 and DE 10 2005 038 712 A1.

[0007] The invention is based on the objective of creating a more cost-effective radio locking system.

[0008] This problem is solved in a generic locking system by the characterizing features of claim 1.

[0009] In the locking system according to the invention, with the features of the main claim, the transmission frequency is adjustable by means of a PLL (phase-locked loop) synthesizer. The PLL synthesizer includes a quartz crystal, which, however, can have a higher tolerance. By using a synthesizer, the required frequency can be set directly. The deviations of the quartz crystal can thus be compensated for within a certain range. Consequently, cost-effective quartz crystals can be used, while still ensuring the narrow bandwidth of the radio channel. Further embodiments of the invention are the subject of the dependent claims.

[0010] According to the invention, the synthesizer is a ΔΣ (Delta-Sigma) fractional N-PLL synthesizer. It has a high resolution, allowing the transmission frequency to be set with high accuracy. Because the transmission frequency is variably adjustable via the synthesizer, the transmitter can be operated with multiple transmission channels, thereby increasing its interference immunity.

[0011] The following can be stated regarding a particularly preferred design of the locking system. Stable operating frequencies for the RF transceiver are generated by a synthesizer using a PLL (phase-locked loop). The high frequency stability is derived from the reference of a crystal oscillator. For the system design, any frequency deviations that may occur due to environmental influences and manufacturing tolerances of the crystals must be taken into account. The initial tolerance is eliminated by an adjustment device in the circuit. However, this incurs costs for the adjustment component, namely the trimmer, as well as time for the usual mechanical adjustment process, including the mechanical locking mechanism (application of locking lacquer). Alternatively, the initial tolerances can also be compensated for by increasing the receiver bandwidth beyond the system's minimum value.However, increasing the receiver bandwidth can lead to certain performance losses for the entire telecommunications transmission link.

[0012] To achieve further improvements, particularly for operating narrowband systems with very precise transmit and / or receive frequencies, the use of a special synthesizer is recommended: a high-resolution ΔΣ-Fractional N-PLL, for example, with a resolution of 0.5 ppm. Due to their accuracy class, quartz crystals used for generating the synthesizer's reference frequency exhibit deviations. Furthermore, additional frequency shifts arise from parasitic effects of the circuitry and the printed circuit board. These can be compensated for by setting a correction value in the frequency setting of the ΔΣ-Fractional N-PLL. The correction value is determined by a calibration measurement, for example, of the transmit frequency, and stored in non-volatile memory.This creates the compensation of high tolerances in quartz crystals in a multi-channel radio system by adjusting initial tolerances of the operating frequency using a ΔΣ-Fractional N-PLL, advantageously resulting in the following:. - avoiding the use of an adjustable capacitor (trimmer) for frequency correction, which means a reduction in component costs, - the elimination of the mechanical adjustment process on the trimmer, thus saving labor costs, - avoiding the change or displacement of the calibrated trimmer due to mechanical shock or vibration during use in the locking system, - The use of cost-effective quartz crystals with large initial tolerance is made possible.

[0013] The advantages achieved with the invention consist in particular of the fact that cost-effective quartz crystals with high tolerance can be used in the locking system. This leads to a reduction in system costs.

[0014] An embodiment of the invention with various further developments and configurations is shown in the drawings and is described in more detail below. The drawings show... Fig. 1 a motor vehicle equipped with a locking system, Fig. 2 a schematic block diagram of the locking system comprising two devices with a diagram for the transmission of signals and Fig. 3 the second mechanism of the locking system in a partially cutaway and schematic view.

[0015] In Fig. Figure 1 shows a motor vehicle 1 with the authorized user 2. The motor vehicle 1 is equipped with a locking system 3 as a door locking system for access authorization. This system comprises a first device 4, designed as a control unit, and an associated second device 5. The second device 5 is designed as an electronic key, an identification (ID) transmitter, a chip card, a smart card, or the like. The second device 5 is in the possession of the authorized user 2, who thus has access to the motor vehicle 1 within a control area 8.

[0016] The first device 4 has at least two states, the first state being a locking state and the second state an unlocking state of the car doors 6. Both devices 4 and 5 have means for transmitting and / or receiving signals 7 by means of an electromagnetic carrier wave for their intended operation. At least one of these signals 7 transmitted between the second device 5 and the first device 4 is a coded electromagnetic operating signal 15 (see Fig. 2) The coded operating signal 15 serves to authenticate the second device 5, whereby, if the second device 5 is authorized, a change in the state of the first device 4 can be effected after a positive evaluation of the transmitted operating signal 15. The transmission of the coded operating signal 15 occurs when the authorized user 2 operates the door handle 16 on the car door 6 or approaches the door handle 16. This triggers the unlocking of the car doors 6 according to the user-independent keyless entry functionality. The transmission of the coded operating signal 15 can also occur automatically without the user 2's intervention as soon as they enter the operating area 8, which, however, will not be considered in further detail below. If the user 2 closes the car doors 6 from the outside, the car doors 6 lock automatically.The automatic locking of the car doors 6 can also occur after the user has left the effective area 8.

[0017] Furthermore, in addition to the keyless entry functionality, remote locking and unlocking of the car doors is also possible, which is achieved by means of... Fig. Three visible, button-like operating elements 9 on the second device 5 can be triggered by the user 2 to grant the user 2 access to the motor vehicle 1. For example, the central locking system can be locked and / or unlocked and the trunk lid opened by manually operating the operating elements 9, by sending corresponding coded operating signals 15 from the second device 5 to the first device 4. The symbols 10 corresponding to these functions are affixed to the operating elements 9.

[0018] The locking system 3 further establishes the driving authorization for the vehicle 1. For this purpose, the first device 4, designed as a control unit, also causes the electronic ignition lock or steering lock to be unlocked and / or locked according to the two states. Likewise, another functionally relevant component of the vehicle 1 can be controlled accordingly by the first device 4. For example, this can enable and / or disable an immobilizer, the engine control unit, or the like. The transmission of the coded operating signal 15 for the authentication of the second device 5 occurs when the authorized user 2 is in the vehicle 1 and activates a start / stop switch 11. This triggers the starting process or similar action of the vehicle 1 according to the KeylessGo functionality.

[0019] Additionally, an emergency operation can be provided, for example in the event of an empty battery of the second device 5, by making the second device 5 as an electronic key insertable into the ignition lock of the motor vehicle 1 for manual operation by the user 2.

[0020] The functionality corresponding to the keyless functionality of the locking system 3 according to the invention will now be explained using the Fig. 2 will be explained in more detail. First, the first device 4 sends a first electromagnetic signal 12, referred to as a wake-up signal, to the associated second device 5 by means of a transmitter / receiver 24 as a means of sending and / or receiving signals. This switches the second device 5 from a standby state with reduced energy consumption to an activated state for intended operation. The first device 4 then sends at least one further, third electromagnetic signal 13, which is also referred to below as the range delimitation signal. This allows the associated second device 5 to determine its location relative to the first device 4. In particular, it can be determined whether the second device 5 is located outside the vehicle 1 and, if so, at which point in the exterior space 23 and / or interior 22 of the vehicle 1.Subsequently, the second device 5 sends a fourth signal 14, containing information about the determined location, to the first device 4 via a transmitter / receiver 17. This signal is also referred to as the response signal. Finally, as already described, the fifth electromagnetic signal, a coded electromagnetic operating signal 15, is transmitted between the first and second devices 4 and 5 for authentication via transmitters / receivers 24 and 17. Signal 15 can, in particular, consist of several sub-signals and be transmitted in bidirectional communication between the two devices 4 and 5. For further details on bidirectional communication, reference is also made to DE 43 40 260 A1.

[0021] The wake-up signal 12 can, for example, contain an identifier for the vehicle type. Upon receipt of the wake-up signal 12, all second devices 5 located within the effective range 8 that belong to the same vehicle type are initially activated. In a further embodiment of the locking system 3, the first device 4 sends a second electromagnetic signal 18 to the second device 5 as a selection signal between the first signal 12 and the third signal 13, as described in more detail below. Fig. 2 can be recognized. The second signal 18 contains information about the more precise identity of the motor vehicle 1. This ensures that only the second devices 5 actually belonging to the first device 4 remain in the activated state. Second devices in the activated state that do not belong to the motor vehicle 1 are returned to the idle state.

[0022] Signal 15 is transmitted as a radio signal, for example in the RF (high frequency) range. The other signals 12, 13, 14, and 18 are also radio signals that can be transmitted as needed in the LF (low frequency) range and / or the RF (high frequency) range. The respective transmitter 17, 24 is operated for the transmission of signals 7 with a transmission channel 19 having a predetermined transmission frequency, as shown schematically in Fig. 3 is indicated. The transmission frequency for transmission channel 19 can be set by means of a PLL (phase-locked loop) synthesizer 21 having a crystal 25.

[0023] Synthesizer 21 may be a Delta-Sigma Fractional N-PLL Synthesizer.

[0024] In a further training, transmitter 17 can be operated with multiple transmission channels 19, 20, 20', so that the operating signal 15 can also be transmitted on the additional transmission channels 20, 20' at different transmission frequencies. It is then possible to transmit the operating signal 15 redundantly on multiple transmission channels 19, 20, 20'. The corresponding transmission frequency for each transmission channel 19, 20, 20' is set using synthesizer 21.

[0025] The invention is not limited to the described and illustrated embodiment. Rather, it also encompasses all technically advanced developments within the scope of the invention defined by the claims. Thus, such a locking system can be used not only in motor vehicles but also for other types of door locks, such as those found on buildings or the like. Reference numeral list: 1 motor vehicle 2 (authorized) users 3 locking system 4 first setup 5 second setup / electronic key 6 car doors 7 Signal 8 Area of ​​influence 9 Actuating element 10 Symbol (on the operating element) 11 Start / Stop switches 12 (first) signal / wake-up signal 13 (third) signal / area boundary signal 14 (fourth) signal / response signal 15 (fifth) signal / (coded) operating signal / code 16 Door handle 17 transmitters / receivers (in the second facility) 18 (second) signal / selection signal 19 transmission channel 20.20' (another) transmission channel 21 (PLL) Synthesizers 22 Interior (of the motor vehicle) 23 Exterior space (of the motor vehicle) 24 transmitters / receivers (in the first setup) 25 Quartz

Claims

Locking system for access and / or driving authorization in a motor vehicle (1) comprising a first device (4) having at least two states and designed as a control device, and a corresponding second device (5), wherein the two devices (4, 5) have transmitters and / or receivers (24, 17) for electromagnetic signals (7) for their intended operation, wherein the transmitter (17) is operated with a transmission channel (19) having a predetermined transmission frequency, and wherein at least one of the signals (7) transmitted between the second device (5) and the first device (4) is a coded operating signal (15) for authenticating the second device (5), such that after a positive evaluation of the transmitted operating signal (15) a change in the state of the first device (4) can be effected by an authorized second device (5), characterized in thatthat the transmission frequency can be adjusted by means of a PLL (Phase-locked Loop) synthesizer (21) having a quartz crystal (25), which is a Delta-Sigma Fractional N-PLL synthesizer. Locking system according to claim 1, characterized in that the transmitter (17) can be operated with multiple transmission channels (19, 20, 20').

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